1,721,014 research outputs found
Quantified seismic anisotropy at different scales: A case study from the KTB crustal segment
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Quantified crack distribution in a KTB core sample: Fabric analyses vs. ultrasonic inversion
No full textShear wave anisotropy of laminated lower crust beneath Urach (SW Germany): a comparison with xenoliths and with exposed lower crustal sections
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Recovering shear wave anisotropy of the lower crust: The influence of systematic errors on traveltime inversion
No full textAligned fractures in carbonate rocks: laboratory and in situ measurements of seismic anisotropy
No full textBy vertical seismic profiling and shear wave analysis we show that a packet of carbonate reservoir rocks, found at nearly 3000 m depth in the North German Basin, is seismically anisotropic. For vertical paths of wave propagation the estimated velocity difference of the split shear waves is 10%. No shear wave birefrigence is observed within the hangingwall which, therefore, has to be regarded as isotropic or transversely isotropic. Additional laboratory investigations of the petrography of drilled carbonate samples and of their seismic velocities show that the anisotropy is most probably caused by subvertical fractures with preferred azimuthal orientation. The strike direction of the aligned fractures determined by analysis of split shear waves is approximately N55 degrees E. This value agrees with recently published directions of maximum horizontal tectonic stress in pre-Zechstein sediments in the eastern part of the North German Basin, but it is in contrast to the world stress map
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